Method for controlling a hydrocarbon synthesis reaction



Se t; 7, 1954 E. F. WADLEY ETAL METHOD FOR CONTROLLING A HYDROCARBONSYNTHESIS REACTION Filed Dec. 29, 1949 3 Sheets -Sheet 2 LlQUiD PRODUCT,U-V. ABSORPTION K AT 258 Ml".

D III T w B S L A A L I! T F A F I c 0 a l N I O M 1 4 8 1 OU '52 T EA rR O N I F E N c 0 H a F R E A o O C 0 m w m w m u w s a 1 s 4 a z oMHIENTORS. Edward E Wadley,

Jarggs A.Anders0n Jr.,

M RM

p 3954 E. F. WADLEY ETAL METHOD FOR CONTROLLING A HYDROCARBON SYNTHESISREACTION Filed Dec. 29, 1949 3 Sheets-Sheet 3 E T A S N E D N O C D E Hs A w n Y F W A 1 c 2 III II N 3 1 O 2 M m A m T A E N H V E R C m n F NE M w O I R A N c w w T P R 4 O S l B A M U w W 4 B 2 U m 9 8 7 6 5 A 30 32323 81:31:; X52358 aux.. wsamw LIQUID PRODUCT, U-V. COEFFICIENT AT232 MP.

FIG. 3.

auvurons. Edward F. Wadley, James A.Anderson J UNITED STATES PATENTOFFICE METHOD FOR CONTROLLING A HYDRO- CARBON SYNTHESIS REACTION EdwardFrank Wadley and James A. Anderson, Jr., Baytown, Tern, assignors toStandard Oil Development Company, Elizabeth, N. 3., a corporation ofDelaware Application December 29, 1949, Serial No. 135,692

6 Claims. (Cl. 260-449) The present invention is directed to a methodfor controlling a hydrocarbon synthesis reaction in which hydrogen andcarbon monoxide react to form hydrocarbons and oxygenated organiccompounds. In practicing the present invention a feed mixture of carbonmonoxide and hydrogen is reacted at a reacting temperature and pressurein the presence of a catalyst selected from group VIII of the periodictable of HzzCo in the reactor feed gas. Other means of reducing carbonformation include the injection of steam into the feed to the reactor.

In accordance with the present invention the formation of carbon in thesynthesis of hydrocarbons and oxygenated organic compounds from carbonmonoxide and hydrogen when metals or compounds of metals from group VIIIof the periodic table, such as the oxides thereof,

whereby oxygenated organic compounds and hyare employed as catalyst, maybe substantially drocarbons are produced and Carbo s fOrmed reduced.This is accomplished by continuously or n d O t t y t A Vaporous streamof at intermittently withdrawing a ortion of the liqleast a portion ofthe yd o is Separated uid hydrocarbon fraction and forming the withfromthe catalyst and the vaporous stream i eX- drawn portion of the liquidhydrocarbon fracposed to a be m of li h h v g W v l th tion into avaporous stream which is exposed to in the range between 225 and 270millimicrons to a beam of light having a wave length in the obtain anelectrical potential which is a funcrange between 225 and 270millimicrons to obtion of the rate of Carbon formation in and on tain anelectrical potential which is a function the catalyst. The carboncontent of the catalyst of the rate of carbon formation in and on the iscontrolled by varying, in response to variacatalyst. The rate ofdeposition of carbon in tions in the electrical potential, a suitableprocand on the catalyst may therefore be controlled ess variable whichafifects the rate of carbon depby varying, in response to variations ofthe elecosition in and on the catalyst. trical potential so obtained,any one or several of The production of liquid fuels by the reaction thefollowing process variables: (a) the H2100 of carbon monoxide andhydrogen using iron ratio in the total feed gas; (11) the total pressurecontaining catalysts is limited in its commercial of the reactor system;or (c) the injection of application by excessive carbon formation in andsteam into the reactor. Other means for changon the catalyst withattendant catalyst disinteing the rate of carbon deposition in and onthe gration. It appears that the carbon is deposited catalyst may alsobe employed in response to On t e t y in e t st es of t e C talyst thevariation of the electrical potential in ac as iron carbide which isconverted to carbon and cordance with my invention. The vaporized causesexpansion of the iron catalyst and resultstream is exposed to a beam oflight having ing disintegration theerof. In conducting such wave lengthsin the range given by passing it Operations y filo-called fl 0 powdertechthrough a sample cell of a spectrophotometer niques the Catalyst ybe rapidly 10st f through which a beam of light is passed. Apore ys tionof the light is absorbed by the hydrocarbon Some of the moreadvantageous catalysts for while the remainder is unabsorbed. Theunthese reactions are iron containing catalysts absorbed light passingthrough the cell in the such as gamma F6203, FesOi, suitably promotedspectrophotometer is converted to an electrical With alkali metalcompounds such as alkali metal potential by well known means such asimpingecarbonates, oxides, hydroxides and various alm; on a h t l t i lwhich causes K metal Salts. eration of the potential. The electricalpotential These Catalysts, however, ve a t y to derived from thespectrophotometer may be amform BXCESSiVE amounts 0f carbon whichresults plified in a, conventional and well known manin the difiicultiesmentioned before. By virtue of ner and impressed upon a recordercontroller the formation of excessive amounts of carbon which in turnactuates a flow control means the reaction frequently becomesuncontrollable, hich causes t admission of extraneous hy resulting in tu o of the Operation. drogen to the feed admixture, thus raising theSeveral methods may be employed for reducing partia1 pressure of thehydrogen in the feed the rate of deposition of carbon in and onhymixture; or the electrical potential through the drocarbon synthesiscatalysts. These methods recorder controller may be caused to operate ainclude increasing the hydrogen partial pressure pressure control meansin the system which in the reactor, either by maintaining the HzICOraises the pressure on the reaction and thus ratio in the reactor feedgas and increasing the raises the partial pressure of the hydrogen intotal reactor pressure, or by increasing the ratio the mixtureundergoing reaction.

The ultraviolet absorption spectra of materials are essentially the samein either the liquid or the vapor phase. It is preferred to use thevapor phase with most plant control processes because of the comparativeease with which vapor phase sample handling systems may be devised forspectrophotometric systems. The liquid phase is generally useful forsystems having low absorption coefficients or low concentration of theabsorbing material. However, the liquid phase may be used for systemshaving relatively high light absorption by employing a constant ratioblending system to dilute the sample with a known amount of a relativelytransparent solvent or by using a sample cell of suitable thickness,probably on the order of less than one millimeter thick.

The invention will be further illustrated by reference to the drawing inwhich:

Fig. 1 is a flow diagram of a preferred mode of practicing theinvention;

Fig. 2 is a chart of data showing the relationship between carbonproduced per cubic meter of carbon monoxide and hydrogen consumed andthe ultraviolet absorption coefiicient of the liquid synthesis productat a wavelength of 258 millimicrons; and

Fig. 3 is a similar chart of data showing the same relationship at awave length of 232 millimicrons.

Referring now to the drawing and particularly to Fig. l, numeraldesignates a feed line through which a mixture of carbon monoxide andhydrogen is introduced into the system from a source not shown. The feedmixture of carbon monoxide and hydrogen may be in proportions in therange from 1:1 to 1:2 and flows by way of line I through a flowcontroller l2 whose function will be described further later on, andthence into line I3 wherein there is suspended in the gaseous mixture acatalyst such as gamma iron oxide in fiuidizable powder form, introducedthereto from catalyst hopper M by line |5. The catalyst introduced intoline l3 by line I5 may be at an elevated temperature sufficient to causereaction of the carbon monoxide and hydrogen to produce hydrocarbons andoxygenated organic compounds. The suspension of catalyst in carbonmonoxide and hydrogen passes by line l3 into a reactor l6 whereintemperatures and pressures are adjusted to allow the reaction to proceedto form a product including hydrocarbons and oxygenated organiccompounds. The temperature in reactor l6 will be in the range from about300 to about 750 F. with pressures from about atmospheric up to as muchas 600 p. s. i. g. Since the reaction of carbon monoxide and hydrogenresults in the liberation of excessive amounts of heat, which, if notremoved, would raise the temperature in reactor l6 drastically,provision is made for removing this heat by circulating a cooling fluid,such as water, through a cooling means illustrated by coil H which islocated in reactor I6. It is understood that while the cooling means hasbeen illustrated by coil l'l, other cooling means may be employed.

The velocity of the catalyst-carrying feed mixture in reactor I6 isadjusted such that a dense phase consisting of catalyst and reactantsand reaction products is formed. The catalyst and the reaction products,as well as unreacted feed mixture, discharge from reactor [6 by line I8in which is located a pressure controller is whose function will bedescribed later. The discharged stream in line l8 passes into a catalystseparator 2|] which may be of the cyclone type which removessubstantially all the catalyst from the product and allows the catalystto drop downwardly from separator 20 into a first catalyst hopper 2|,while the reaction product and unreacted gases pass by way of line 22into a second catalyst separator 23 to cause removal therefrom ofcatalyst fines. These fines may be discharged from separator 23 by line24 controlled by valve 25, or may be routed back to hopper 2| by line 26controlled by valve 27.

The products, including unreacted gases, discharged from separator 23 byline 28 are cooled by passage through a cooler 29 and then discharged byline 30 into a product separator 3| wherein a separation is made betweengaseous and liquid products and where water is removed as will bedescribed further.

The catalyst in hopper 2| may have deposited thereon, besides the carbonwhich is laid down by the reaction, heavy paraifinic hydrocarbons of awaxy nature. Since these heavy waxy hydrocarbons may interfere with theefliciency of the reaction, it may be desirable to remove them beforethe catalyst is returned to reactor |6, as will be described. Therefore,it may be desirable to withdraw all or part of the catalyst in hopper 2|by line 32 controlled by valve 33 into a wax removal unit 34 wherein aportion or all of the catalyst may be treated with a suitable solventsuch as middle oil, benzene, pyridine, alcohols, or liquid substancesformed during the reaction itself for removal of waxy hydrocarbons,after which the catalyst, substantially free of wax is discharged byline 35 into hopper Id for use in the synthesis reaction as has beendescribed. It is understood that wax removal unit 34 is indicatedschematically and will include all auxiliary facilities necessarytherefor. Suitable apparatus for removing wax is described in U. S.2,159,140.

Since it may be unnecessary to treat all of the catalyst for removal ofwax, line 33 which is controlled by valve 31 is provided whereby aportion of the catalyst may be caused to by-pass unit 34 and dischargedirectly into line 35 for routing to hopper M.

In separator 3| a separation is made between gaseous and liquidproducts, the gaseous material, including unreacted carbon monoxide andhydrogen and carbon dioxide formed in the reaction, is removed fromseparator 3| by line 38 controlled by valve 39 and may be recycled toreactor 15 by way of lines II and It for re-use in the process. In someinstances it may be desirable to discharge a portion of the recycled gasand, therefore, line 4!! controlled by valve 4| is provided.

In separator 3| a separation is also made between liquid hydrocarbonsand water produced in the reaction. The liquid hydrocarbons and thewater will contain oxygenated organic compounds with the more watersoluble compounds found in the water layer, while the more hydrocarbonsoluble are found in the hydrocarbon layer. The water layer is withdrawnfrom separator 3| by line 42, while the hydrocarbon layer is withdrawnby line 43 controlled by valve 44. The greater portion of thehydrocarbon stream is routed by line 45, controlled by valve 46, to afractionation system, not shown, while a minor portion is employed tooperate the control system, as will be described further.

During the reaction in reactor I6 a considerable amount of carbon isformed in and on the catalyst. Heretofore the only known way todetermine the amount of carbon on the catalyst was to withdraw a portionof the catalyst from the reaction system and test it for carbon content.It has now been found, however, that the rate of carbon formation on thecatalyst employed in reactor I6 in the synthesis of organic materialsfrom carbon monoxide and hydrogen is related to the concentration ofconjugated materials in the synthesis product. Thus, by determining theamount of conjugated materials in the synthesis product it is possibleto determine the rate at which carbon is formed in and on the catalyst.This discovery is employed in the practice of the present invention tocontrol the synthesis operation by varying the hydrogen partialpressure, which in turn results in the control of the carbon content, inresponse to variations in the concentration of conjugated materials inthe hydrocarbon product. To this end a portion of liquid hydrocarbonproduct in line 63 passes into a vaporizer M provided with a heatingmeans illustrated by coil 48 through which a heating material iscirculated to cause heating to approximately 500 F. and to causevaporization thereof. The vaporized hydrocarbon stream discharges intoline 49 provided with a pressure controller 59 into an ultra-Violetspectrophotometer 5|. Ultraviolet spectrophotometer 5I employs a samplecell having a thickness of the order of 0.25 cm. maintained at apressure of about 100 millimeters mercury absolute, the pressure beingcontrolled by pressure controller 50, and maintained by a vacuum pump 52connected by line 53 to vessel 5t, vessel 5c in turn connects by line 55to spectrophotometer 5| The reduced pressure in tank 54 causes pressurecontroller 50 to be operated. After the vaporized stream has passedthrough the sample cell in spectrophotometer 5| it may be dischargedfrom the system by line 56.

It will be understood that ultraviolet spectrophotometer 5I comprisesall auxiliary equipment usually associated with such ultravioletspectrophotometers. A typical detecting and recording system forultraviolet light is described in an article by E. J. Rosenbaum and L.Stanton entitled Continuous recording ultraviolet spectrophotometer andpublished in Industrial and Engineering Chemistry, Analytical Editionfor October 1947, pages 794 through 798. The unabsorbed light isconverted by means of an instrument of this type into an electricalpotential which is fed by way of conductor 51 into a recorder controllerdevice 56 which may be employed to convert the electrical potential intomechanical movement or displacement. Such a recorder controller may beillustrated by the Brown electronic continuous balance potentiometercontroller in which an incoming D. C. signal is converted to an A. C.signal by a vibrator and is amplified electronically. The amplifiedsignal is then caused to drive a reversible motor whose shaft ismechanically connected to a recording pen and potentiometer slide wire.The output of the potentiometer is applied in opposition to the D. C.signal from the spectrophotometer so that any diiference between thepotentiometer and analyzer signals will be amplified and cause arotation of the motor to bring the potentiometer and the anlyzer signalsinto exact balance.

In this way, the recorder controller pen deflects by an amount which isproportional to the absorption of light by the vapor stream passingthrough the sample cell of spectrophotometer 5|. As pointed outpreviously, this absorption, which is a function of the conjugatedorganic compounds content of the reactor product stream in line 43, isdirectly related to the rate at which carbon is formed on the catalystin reactor I6. The mechanical movement produced in the recordercontroller is arranged to change the position of a flapper and nozzlearrangement well known in the instrument art for operating, by means ofcompressed air, either flow, or pressure, controllers as will bedescribed further. Leading from recorder controller 58 to pressurecontroller I9 in line I8 is a conduit or means 59, controlled by valve60, by means of which the potential from spectrophotometer 5| may becaused to operate pressure controller I9. There is led from recordercontroller 58 a conduit 6| controlled by valve 62 to a flow controller63 which is located in line 64 and which connects into line I I. Line 64connects to a source of auxiliary hydrogen supply, not shown. Aconventional flow controller which may be employed in the practice of myinvention is described in Industrial Instruments for Measurement andControl, by Rhodes, McGraw-Hill Book 00., first edition, New York, 1941,page 489.

Although the present invention has been illustrated to show the controlof the rate of carbon formation by using the ultravioletspectrophotometer and associated equipment to control hydrogen partialpressure, there are other means for controlling the rate of carbonformation which may be readily controlled by the spectrophotometer andassociated control apparatus such as water or steam injection into thefeed gas to the reactor. This may be further illustrated by referring toFig. 1 wherein line 68 containing controller 69 is a source of steamwhich may be placed directly into the feed in line II. Flow controller69 is connected to the recordercontroller 58 by means of line I6 throughwhich the controlling impulse is transmitted and will act to regulatethe amount of steam placed into the feed.

As stated before, the rate of carbon formation on the catalyst inreactor I6 may be determined by the conjugated material content of theproduct in line 43. Therefore, in operation of the present invention thedeposition of carbon in and on the catalyst during the reaction ofcarbon monoxide and hydrogen in reactor I6 is controlled by subjecting aportion of the naphtha withdrawn from separator 43 to vaporization toform a vaporized stream which is passed through a sample cell andultraviolet spectrophotometer 5I to cause absorption when subjected tolight at a wave length in the range between 225 and 270 millimicrons. Atthis wave length a portion of the light is absorbed which is a functionof the content of conjugated materials in the vaporized stream which inturn is a function of the carbon formed on the catalyst in reactor I6.By means of the detector which is exposed to the unabsorbed light, thedegree of absorption of light of the specified wave length by theconjugated material may be converted to an electrical potential which,as has been explained, is amplified and impressed on recorder-controller58, which, in turn, may cause pressure controller I9 or flow controller63 to operate. If recordercontroller 58 is connected by conduit 6| andvalve 62 to flow controller 63 a change in the concentration ofconjugated materials in the stream flowing through line 43 will causethe recordercontroller to transmit a signal to flow controller 63 which,in turn, will admit hydrogen to line H through line 62. Admission ofhydrogen will raise the partial pressure of hydrogen in the mixtureundergoing reaction in reactor 16, and, in turn, will decrease theformation and deposition of carbon in the catalyst in reactor [6. On theother hand, rather than controlling the flow of auxiliary hydrogen toline H, the same end may be achieved by closing valve 62 in line BI andopening valve 50 in conduit 59 communicating recorder controller 58 withpressure controller i8. By causing the recorder-controller to actuatepressure controller IS the pressure in reactor [8 may be increased andthus partial pressure of hydrogen in the reactor l6 may also beincreased, thus suppressing the formation of carbon on the catalyst inreactor 16. Rather than cause pressure controller H) to operate,recordercontroller 58 may be employed to increase the flow of feedmixture to reactor 46 while maintaining the pressure therein constant.This may be accomplished by causing the impulse from recorder 58 toactuate controller l2 through conduits 59 and 65 whereby the same endmay be achieved.

If the rate of carbon formation should become so excessive as toendanger the reaction system or the catalyst, recorder-controller 58 maybe utilized to produce an impulse which will be transmitted through line66 to flow controller 52 to stop the flow of feed to the reactor. Underordinary operating conditions, recorder-controller 58 will act only toadjust the partial pressure of the hydrogen by either increasing theamount of hydrogen in the feed or increasing the total pressure of thefeed in the reactor.

Oxygenated hydrocarbons such as those found in typical hydrocarbonsynthesis naphthas do not interfere significantly with ultravioletabsorption measurements in the 225 to 270 millimicron ultravioletregion; therefore, the preferred application of the present inventionhas been illustrated by utilizing a stream from the synthesis unit whichincludes the total liquid product. The absorption of the oxygenatedcompounds is negligible for the wave length region used for the controlinstrument; therefore, a very satisfactory control may also be obtainedby using in the control system a liquid hydrocarbon stream free ofoxygenated compounds.

In order to illustrate the invention further, ref erence will now bemade to Figures 2 and 3 which are in the form of charts presenting agraph of data wherein the grams of carbon formed during a given timeinterval or reaction period per cubic meter of hydrogen and carbonmonoxide consumed is plotted, respectively, against the ultravioletcoefficient absorption constant at 258 millimicrons and 232 millimicronsfor a liquid product similar to that withdrawn by line 43. It will beseen from an examination of the data in Figures 2 and 3 that the rate ofcarbon formation varies directly with the ultraviolet absorptioncoefficient at wave lengths of light of 232 and 258 millimicrons.

It has been observed that the absorption coefficient at other wavelengths in the range of 225 to 270 millimicrons also varies inproportion with the carbon formation. Thus, it is not necessary to usemono-chromatic radiation with a wave length of exactly 232 or 258millimicrons but radiation anywhere within the range of 225 to 270millimicrons is satisfactory. Therefore, the absorption coefiicient atwave lengths between 225 and 27-0 millimicrons allows a direct value ofthe rate at which carbon is formed in reactor 16 to be obtained. In viewof this relationshi it is possible to convert the output from aspectrophotometer, through which a vaporous stream produced in such anoperation is passed, to an electrical potential which will allow theregulation of the partial pressure of the hydrogen in the feed mixtureand thus will cause regulation of the carbon content of the catalyst.

The present invention has been illustrated by employment of group VIIIcatalysts such as iron oxide and especially gamma iron oxide and F6304.It is to be understood that other of the group VIII catalysts may beemployed such as oobalt, nickel and ruthenium, either as the metals oroxides thereof. It is also to be understood that iron may be used as themetal or oxides. Catalysts of this type may be suitably promoted withalkali metal compounds such as the sodium, potassium and lithiumcarbonates, oxides, hydroxides, as well as the fluorides, chlorides andother salts of the alkali metals mentioned before.

The present invention has been described and illustrated with referenceto the fluidized powder technique. When such an operation is employedthe catalyst may have particle diameters ranging up to 200 microns withthe major portion of the catalyst having diameters ranging from 20 tomicrons to allow fiuidization of the catalyst powder.

Although the invention has been illustrated by reference to thefluidized powder technique where the catalyst is suspended in the feedgases, it is to be clearly understood that the operation may beconducted by maintenance of the catalyst in beds in catalyst cases. Insuch operations the catalysts may be in the form of pills, pellets orrods. In fixed bed operations it may be desir able to employ a pluralityof catalyst cases such that the catalyst may be treated in one while theother is on the reaction cycle.

The nature and objects of the present invention having been completelydescribed and illustrated, what I wish to claim as new and useful and tosecure by Letters Patent is:

1. In a process in which a gaseous feed mixture of carbon monoxide andhydrogen is reacted at a reaction temperature and pressure in a reactionzone in the presence of a catalyst comprising the metals and oxidesthereof selected from group VIII of the periodic table to form a productcomprising hydrocarbons and oxygenated organic compounds in which carbonis deposited in and on said catalyst and said product is separated fromsaid catalyst, the steps of cooling said product to form a liquefiedproduct comprising hydrocarbons and oxygenated organic compounds,exposing at least a portion of said liquefied hydrocarbon-containingproduct to a beam of light having a wave length in the range of 225 to270 millimicrons, absorbing at least a portion of said light and leavingan unabsorbed portion, obtaining from said unabsorbed portion anelectrical potential which is a function of the rate at which carbondeposits in and on said catalyst and increasing the partial pressure ofhydrogen in said feed mixture in response to increases in saidelectrical potential and decreasing the partial pressure of hydrogen insaid feed mixture in response to decreases in said electrical potential,whereby the rate of carbon deposition in and on the catalyst is reduced.

2. A process in accordance witth claim 1 in which the partial pressureof hydrogen in the feed mixture is increased by adding hydrogen thereto.

3. A process in accordance with claim 1 in which the partial pressure byhydrogen in the feed mixture is increased and decreased by increasingand decreasing the pressure in the reaction zone.

4. In a process in which a gaseous mixture of carbon monoxide andhydrogen is reacted at a reaction temperature and pressure in a reactionzone in the presence of a catalyst comprising the metals and oxidesthereof selected from group VIII of the periodic table to form a productcomprising hydrocarbons and oxygenated organic compounds and in whichcarbon is formed in and on said catalyst and said product is separatedfrom said catalyst, the steps of cooling said product to form aliquefied product comprising hydrocarbons and oxygenated organiccompounds, withdrawing a stream of said liquefied hydrocarbon-containingproduct, vaporizing said withdrawn stream, exposing said vaporcus streamto a beam of light having a wave length in the range between 225 and 270millimicrons, absorbing at least a portion of said light, a portion ofsaid light being unabsorbed, converting said unabsorbed portion of lightto an electrical potential which is a function of the amount of carbonformed in and on said catalyst, and increasing the partial pressure ofhydrogen in said mixture in response to increases in said electricalpotential and decreasing the partial pressure of hydrogen in said feedmixture in response to decreases in said electrical potential, wherebythe rate of canbon deposition in and on said catalyst is reduced.

5. A process in accordance with claim 4 in which the partial pressure ofhydrogen in the feed mixture is increased by adding hydrogen thereto.

6. A process in accordance with claim 4 in which the partial pressure ofhydrogen in the feed mixture is increased and decreased by increasingand decreasing the pressure in the reaction zone.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,251,554 Sabel et a1 Aug. 5, 1941 2,257,457 Fischer et a1Sept. 30, 1941 2,271,259 Herbert Jan. 27, 1942 2,276,274 Keith, Jr Mar.17, 1942 2,318,626 Pier et a1 May 11, 1943 2,459,404 Anderson, Jr Jan.18, 1949 2,462,946 Coggeshall et al. Mar. '1, 1949 2,462,995 Ritzmann 1Mar. 1, 1949 2,518,307 Grobe Aug. 8, 1950 2,589,925 Cain et a1 Mar. 18,1952

1. IN A PROCESS IN WHICH A GASEOUS FEED MIXTURE OF CARBON MONOXIDE ANDHYDROGEN IS REACTED AT A REACTION TEMPERATURE AND PRESSURE IN A REACTIONZONE IN THE PRESENCE OF A CATALYST COMPRISING THE METALS AND OXIDESTHEREOF SELECTED FROM GROUP VIII OF THE PEROIDIC TABLE TO FORM A PRODUCTCOMPRISING HYDROCARBONS AND OXYGENATED ORGANIC COMPOUNDS IN WHICH CARBONIS DEPOSITED IN AND ON SAID CATALYST AND SAID PRODUCT IS SEPARATED FROMSAID CATALYST, THE STEPS OF COOLING SAID PRODUCT TO FORM A LIQUEFIEDPRODUCT COMPRISING HYDROCARBONS AND OXYGENATED ORGANIC COMPOUNDS,EXPOSING AT LEAST A PORTION OF SAID LIQUEFIED HYDROCARBON-CONTAININGPRODUCT TO A BEAM OF LIGHT HAVING A WAVE LENGTH IN THE RANGE OF 225 TO270 MILLIMICRONS, ABSORBING AT LEAST A PORTION OF SAID LIGHT AND LEAVINGAN UNABSORBED PORTION, OBTAINING FROM SAID UNABSORBED PORTION ANELECTRICAL POTENTIAL WHICH IS A FUNCTION OF THE RATE AT WHICH CARBONDEPOSITS IN AND ON SAID CATALYST AND INCREASING THE PARTIAL PRESSURE OFHYDROGEN IN SAID FEED MIXTURE IN RESPONSE TO INCREASES IN SAIDELECTRICAL POTENTIAL AND DECREASING THE PARTIAL PRESSURE OF HYDROGEN INSAID FEED MIXTURE IN RESPONSE TO DECREASES IN SAID ELECTRICAL POTENTIAL,WHEREBY THE RATE OF CARBON DEPOSITION IN AND ON THE CATALYST IS REDUCED.